Orkos

Ares wanted to create the perfect warrior so he could use this warrior to overthrow Zeus and bring down the walls of Olympus. To accomplish this, he and the queen of the Furies, Alecto, mated and conceived a child, Orkos. However, much to Ares' disappointment, Orkos was not what he hoped he would be, and disowned him.
The Furies, however, spared him and made him the oath-keeper. Orkos, despite his heavy burden, was eager to please those who he thought loved him. However, Orkos saw the injustice in the Spartan Kratos' oath and turned against his mothers. With the help of the Oracle of Delphi, he tried to warn Zeus of Ares' plot, but the Furies were sent after him. The Oracle was punished for the attempt, while Orkos managed to reach Kratos, who was being hunted down by the Furies for breaking his blood oath to Ares.

Orkos' first meeting with Kratos ended up alarming him and causing the Spartan to attack, but Kratos ceased his onslaught when Orkos explained his motives. However, in Delos, the duo was captured by the Furies, who then had Kratos imprisoned within Aegaeon.

Death

After escaping the Hecatonchires and defeating the Furies, Kratos returned to his home in Sparta, with Orkos meeting him there. Although the shade praised the warrior on his victory, he soon revealed that, before they were defeated, the Furies had made him Kratos' oath-keeper once again, indicating that despite their efforts, Ares would retain control over both of them, lest the Spartan kill Orkos.
Orkos, begging Kratos to give him an honorable death, handed his blade over to the warrior, who then proceeded to stab him in the stomach, killing him and freeing them both of their respective bonds to Ares. After which, Kratos burned down his home, with the corpse of Orkos inside of it, before departing.

In chapter 19 of Rise of the Warrior, it is revealed that the cloaked figure who follows the Warrior is Orkos.